Pressure switch



Nov. 1, 1938. H. VAN VALKENBURG AL 2,135,265

PRESSURE SWITCH Filed Jan. 8, 1936 INVENTOR5- ll lJk .7110: 6% fscbz fen ATTORNEY Patented Nov. 1, 1938 UNITED STATES PATENT oFrlcs PRESSURE SWITCH poration of Michigan Application January 8, 1936, Serial No. 58,070

6 Claims.

This invention relates generally to an electric pressure switch and more particularly to an electric switch wherein the operation of making and breaking an electric circuit is responsive to fluid pressure exerted upon a pressure responsive element.

One object of the invention is to provide an improved form of pressure switch of small size which shall be extremely rugged and of a simple form, economical to manufacture.

Another object of the invention is to provide a pressure switch adaptable for relatively high pressures which shall be small in size and which shall use a relatively light reactive spring.

Another object of the invention is to provide a pressure switch with means to entrap and vent any moisture leaking past the operating element.

Other objects and features of this invention will be readily apparent to those skilled in the art from the following specification and appended drawing illustrating certain preferred embodiments of the invention to which:

Figure l is a side elevational view of the pressure switch according to the present invention showing a conventional attachment to a fragmentary portion of a welder gun in section.

Figure 2 is a sectional view on the line 2-2 of Figure l.

Figure 3 is a sectional view on the line 3-3 of Figure 2.

The pressure switch has been shown in Figure l. as attached to a conventional fragmentary portion of a welder gun but while the switch, due to its simple and rugged construction, readily adapts itself to this specific use, it is to be understood that the switch is of general application and may be used for any service where actuation in response to pressure is desired.

The fragmentary welder gun handle is designated generally by the reference numeral l To this is connected a source of air or other fluid pressure through the flexible tube 2. This fluid pressure is lead through the handle to a valve, not shown, and thence to a cylinder 3 containing the piston 4 operatively connected to the welding eletrodes, not shown. The remaining structure of the welder gun is of conventional form and forms no part of the present invention. A passage 5 in the handle leads from the cylinder 3 to a seat 6 into which the threaded end of the pressure switch 8 is rigidly secured. A washer 9 joint. The back of the handle may be provided with an integral casing ll slightly larger in internal diameter than the outer diameter of the switch 8 to protect the switch from impact.

The switch 8 comprises a tubular metallic body portion 12 having a heavier tubular portion l3 rigidly secured thereto at one end as by welding. The opposite end of the tubular portion i2 is threaded to receive the closing cap M. Within the tubular portion l2, remote from the open end thereof, is disposed an insulating tube it of fibre or other material. Mounted against this insulating tube is a cylindrical insulating block i6 maintained in the position illustrated by a set screw ill. Exteriorly of the cylinder it is an additional insulating tube l3 fitting closely within the body portion l2.

Stationary contacts is and 1 2! are rigidly mounted on connectors 23 and 24 leading through the block l6 and terminating in attaching prongs 25 at the other side thereof. These connectors and contacts may be rigidly secured to the block "i as by means of rivets 22.

Between the block it and the portion i3 is loosely disposed an insulating disc 26 having central recesses in its opposite faces. Between the disc 26 and the block 56 is disposed a movable contact 27 formed of a composite disc having a backing portion 2d of brass and a contact surface 29 of silver. It is of course understood that this movable contact may be formed of any other material desired; the composite brass and silver contact being cited as a specific example. A double headed rivet 3i is placed centrally of the movable contact and the front head is received and guided in the recess in the corresponding face of the disc 26. The opposite head of the rivet in the disc is surrounded by and guides a spring 32 which biases the disc 2T to its open position. The spring 32 is disposed within an opening 33 in the block l6 and is stressed at its opposite end by an adjusting screw 34 threaded within the opening 33 and readily adjustable from the open end of the switch to vary the pressure exerted by the spring 32 upon the contact 21.

Withinthe portion l3 are disposed two cylindrical bushings 35 and 36 separated by a cylindrical spacer 37. The elements 35, 36 and 31 have the same exterior diameter corresponding to the interior diameter of the portion l3. The interior diameter of the bushings 35 and 36 corresponds very closely to the .exterior diameter of the elongated plunger or piston 38 disposed therein. The spacer 31 has an interior diameter considerably greater than the bushings and 36 and forms an annular recess 39 surrounding the plunger 38. Vent openings 4| leading from the exterior oi. the switch to the recess 39 are provided through the portion i3 and the spacer 31. The openings 4| vent into the exterior annular recess 42 in portion IS. The interior end of the plunger 38 is swedged over a disc 43 or is otherwise rigidly secured thereto and the disc prevents the withdrawal of the plunger backwardly through the cylinders formed by the bush- 1 The interior end of the plunger ings 35 and 31. 3B is received within the recess in the corresponding face of the disc 26. Adjacent to the open end of the tube l2 space is provided for the reception of a connecting plug 44, of conventional form, connected to the circuit wires 45 and provided with internal contacts, not shown, engaging the prongs 25. A conductor clamp 46 is provided having complementary sections" and 48 provided with flanges 49 received under the cap i4 and with cooperating lugs receiving studs 5| to draw the sections tightly about the conductor 45. A washer 52 may be provided intermediate the plug 44 and the flanges 49. A flat tool engaging portions 53 may be provided adjacent to 'the openable end of the switch providing means for securely threading it into place. Venting holes 54 may be provided in casing l to drain of! any moisture vented through the openings 4|.

The operation of the switch should be readily apparent. In the specific application thereof disclosed, the switch is adapted to initiate the welding cycle when sufllcient pressure is exerted by the welding electrodes. The value of the pressure at which the switch will be operated to close the contacts is determined by the bias exerted by the spring 32. This is adjustable by means of the screw 34 to set the switch for operation at any desired pressure When the pressure within the cylinder 3 builds upsuillciently, the force exerted by the plunger 38 will be suflicient to overcome the spring bias and will move the contact disc 31 into engagement with the stationary contacts l9 and 2|, whereupon the circuit will be completed and the welding cycle initiated. It is understood of course that the function of the pressure switch in this specific application is to energize the control circuit for the switching elements which supply the current to the welding electrodes.

There is included in most air-pressure lines moisture from condensation or other causes which might leak past the plunger 34. The recess 39 and the vents 4| are for the purpose of trapping this moisture and leading it away from the internal parts of the switch. The recess 42 lessens the possibility of blocking the vents 4| by contiguous surfaces.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. A pressure switch comprising a tubular body portion, an insulating block in said body portion and dividing it into two chambers, a tubular insulating liner in each of said chambers, spaced stationary contacts supported by said block in one of said chambers and having connecting portions passing through the block and terminating in attaching prongs in the second chamber, an operating plunger at the end of said one chamber, an insulating washer in said one chamber engaged at one side by said plunger, a bridging contact disc floatingly supported by the opposite side of said washer, and a spring biasing said disc, washer and plunger away from said stationary contacts.

2. A pressure switch comprising a tubular body portion, an insulating block in said body portion and dividing it into two chambers, spaced stationary contacts supported by said block in one chamber, a bridging contact floatingly mounted in said one chamber, a spring biasing said bridging contact and having adjusting means mounted in said block and accessible from the second chamber, a pressure responsive plunger at the end of said one chamber for moving said bridging contact against the bias of said spring, connecting portions leading from said stationary contacts through said block. into said second chamber, and a plug connector adapted to be received within said second chamber and engaged with said connecting portions, removal of said plug permitting ready adjustment of said spring from said second chamber to varying the pressure necessary to operate the switch.

3. A pressure switch comprising a tubular body portion, stationary and movable contacts mounted within said body portion, means biasing said movable contact to one position, pressure responsive means for moving said movable contact against said bias, connectors disposed within said body portion and connected to the switching parts, an attachment plug removably mounted within said body portion and engaging said connectors, a split washer provided with flanges adapted to be clamped about a cable leading to said plug, and a closure for said body portion maintaining said plug in connecting position therein and clamping said split washer in cablestrain absorbing position.

4. A pressure switch comprising a tubular body portion, an insulating block in said body portion and dividing it into two chambers, a pair of stationary contacts supported by said block in one chamber, a bridging contact fioatingly mounted in said one chamber, an opening through the central portion of said block between said chambers, a spring disposed in said opening and bearing against'said bridging contact, an adjusting screw threaded into said opening behind said spring and readily accessible from the second chamber, a pressure responsive plunger at the end of the body portion adapted to move said bridging contact against the bias of said spring, connectors leading from said stationary contacts through saidblock and terminating in attaching prongs in said second chamber and a cap ior said body portion adapted to secure a plug connector within said second chamber.

5. In a pressure switch, stationary and movable contacts, means biasing said movable contact to one position, an elongated piston for moving the movable contact against said bias, a cylinder in which said piston moves, said cylinder being formed of an outer jacket and an internal bushing forming the cylinder wall proper and having intermediate its ends an annular recess around the piston, said jacket having openings.

leading from said recess to vent moisture trapped therein, said bushing being formed of three tubular parts of the same external diameter, the middle part having a larger internal diameter than the end parts to form the recess, the middle part having openings aligning with the openings in the Jacket.

6, In a pressure switch, stationary and movaround the piston, said jacket having an annular recess in its outer surface and openings connecting said inner and outer recesses to vent moisture trapped within the inner recess.

HERMON L. VAN VALKENBURG. CARL A. BCHAEFER. 

